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Long afterglow phosphorescent sensor materials for fiber-optic thermometer

Shinshu University, Shonai, Nagano, Japan
Review of Scientific Instruments (Impact Factor: 1.58). 04/2003; 74(3):1344 - 1349. DOI: 10.1063/1.1540719
Source: IEEE Xplore

ABSTRACT Long duration phosphorescent SrAl 2 O 4 phosphors doped with various auxiliary activators (Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) have been evaluated for the fiber-optic thermometer application. In this thermometer, temperature was measured based on the temperature dependence of the lifetime and/or intensity of the afterglow phosphorescence which was dominated by the thermal excitation of trapped carriers. Characteristics of the long phosphorescent fiber-optic thermometer are quite different from those of the conventional thermometer using fluorescent lifetime of the phosphors. Lifetime and intensity of the afterglow phosphorescence from the long afterglow phosphorescent sensor heads show large positive temperature coefficients in the narrow temperature region around room temperature. Sensitivity and temperature range of the long phosphorescent fiber-optic thermometer depend strongly on the trap depth and the trap density of phosphors. Since the trap depth and the trap density vary with auxiliary activator elements, a variety of fiber-optic thermometers with high sensitivity in various temperature ranges will be able to be developed using Eu 2+ doped SrAl 2 O 4 codoped with various auxiliary activator Ln 3+ ions (Ln=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). © 2003 American Institute of Physics.

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    • "In the fluorescence thermometer, phosphor used as a sensor material is responsible for the accuracy and the sensitivity of the measurements. Among many phosphors used in thermosensors , long afterglow phosphorescent SrAl 2 O 4 and CaAl 2 O 4 based phosphors are found to be a highly sensitive sensor material in the fluorescence thermometer because of its extremely long fluorescence lifetime [2] [3] [4] [5] [6] [7] [8]. "
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    ABSTRACT: Long afterglow phosphorescent SrAl2O4 and CaAl2O4 based phosphors are found to be a useful sensor head material in the fluorescence thermometer because of extremely long fluorescence lifetime. Highly sensitive temperature sensor can be developed based on temperature dependence of afterglow intensity of long afterglow phosphor. Sensitivity of long afterglow phosphorescent SrAl2O4:Eu, Ln and CaAl2O4:Eu, Ln based phosphors are considered to be dominated by depth of the hole traps generated by doped rare-earth elements.
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    ABSTRACT: "October 2005" Thesis (M.Phil.)--The Hong Kong Polytechnic University, 2006. Includes bibliographical references.
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    ABSTRACT: A fibre-optic thermometer using newly developed phosphor sensor materials is described. A highly sensitive fibre-optic fluorescence thermometer is developed using chromium ion (Cr3+) doped phosphor crystals with a longer lifetime than that of conventional ruby sensors. Long fluorescent europium doped strontium aluminate phosphors co-doped with various auxiliary activators (SrAl2O4:Eu2+, Ln3+, Ln = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), were also grown and evaluated. In the fibre-optic thermometer using Cr3+ doped phosphor, PL lifetime decreased at temperatures ranging from 270 K to 750 K. The sensitivity of the fibre-optic thermometer varies with the host materials of Cr3+ ions. In the fibre-optic thermometer using SrAl2O4:Eu2+, Ln3+ doped phosphor, the value and lifetime of afterglow phosphorescence from the SrAl2O4:Eu2+, Ln3+ phosphors varied greatly in the narrow temperature region because the afterglow phosphorescence was dominated by thermal excitation of trapped carriers. Since the trap depth and the trap density depend on auxiliary activator elements, the sensitivity and temperature range of the fibre-optic thermometer using SrAl2O4:Eu2+, Ln3+ phosphors varied with auxiliary activator elements of SrAl2O4:Eu2+, Ln3+ phosphors.
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